The 1780 Atlantic hurricane season ran through the summer and fall in 1780. The 1780 season was extraordinarily destructive, and was the deadliest Atlantic hurricane season in recorded history, with over 28,000 deaths. Four different hurricanes, one in June and three in October, caused at least 1,000 deaths each; this event has never been repeated, and only in the 1893 and 2005 seasons were there two such hurricanes. The season also had the deadliest Atlantic hurricane of all time, the Great Hurricane of 1780. Only one of the known storms was not a hurricane.

The Atlantic hurricane season is the period in a year, from June 1 through November 30, when tropical or subtropical cyclones are most likely to form in the North Atlantic Ocean. These dates, adopted by convention, encompass the period in each year when most tropical cyclogenesis occurs in the basin. Even so, subtropical or tropical cyclogenesis is possible at any time of the year, and often does occur.